libstdc++-v3/testsuite/24_iterators/associated_types/iterator.traits.cc

   1 // Copyright (C) 2020-2021 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18 // { dg-options "-std=gnu++2a" }
  19 // { dg-do compile { target c++2a } }
  20
  21 #include <iterator>
  22
  23 struct bidi_iterator
  24 {
  25   // No nested reference and pointer types.
  26   // No iterator_category.
  27
  28   // cpp17-iterator requirements:
  29   int&           operator*() const;
  30   bidi_iterator& operator++();
  31   bidi_iterator  operator++(int);
  32
  33   // cpp17-input-iterator requirements:
  34   friend bool operator==(const bidi_iterator&, const bidi_iterator&);
  35   using difference_type = long long;
  36   using value_type = int;
  37
  38   // cpp17-forward-iterator requirements:
  39   bidi_iterator();
  40
  41   // cpp17-bidirectional-iterator requirements:
  42   bidi_iterator& operator--();
  43   bidi_iterator operator--(int);
  44 };
  45
  46 void
  47 test01()
  48 {
  49   // PR libstdc++/97935
  50   // Missing subsumption in iterator category detection
  51   using namespace std;
  52   static_assert(__detail::__cpp17_bidi_iterator<bidi_iterator>);
  53   static_assert(same_as<iterator_traits<bidi_iterator>::iterator_category,
  54                         bidirectional_iterator_tag>,
  55                 "PR libstdc++/97935");
  56 }